Alan de Percy, "The Great Alan"; seems to have been of age in 1100, when he was party to a dispute with the Bishop of Durham which was resolved in the Bishop's faour by William II (Rufus); a benefactor to St Peter's Hosp, York; married Emma, daughter of Gilbert de Gant (himself son of Baldwin, Count of Flanders, and nephew of Queen Matilda or Maud, wife of William I The Conqueror) by Gilbert's wife Alice, herself daughter of Hugh de Montfort, and was probably dead by Dec 1135. [Burke's Peerage]
Note: the ancestry for Gilbert de Gant given above, does not agree with Ancestral Roots.